Vitamin D – Benefits and Roles in Sports – Part 2


This is the past two of a sequel narrative on “Vitamin D – benefits and roles in Sports”. Here’s the link of part 1. Written by Dr. Ana

Although, there is sufficient evidence suggesting Vitamin D deficiency is the most common nutritional phenomena, and is likely to be the most common medical condition in the world. The lack of a proper health guideline suggesting the optimal value to be achieved of Vitamin D for its benefits is still widely debated.

The major cause for the decrement of vitamin D has been the lack of appreciation that the body requires 5- to 10- fold higher intakes than is currently recommended by health agencies.

Confusing status of Vitamin D deficiency level

Adding to the confusion, Zittermann defines ”optimum vitamin D status” between 100-250 nmol.L-1, whereas the US Institute of Medicine (IOM) defines inadequate vitamin D status as <50 nmol.L-1, suggesting potential adverse events when levels are >125 nmol.L-1. The Scientific Advisory Committee on Nutrition (SACN) and the Food Standards Agency (FSA) of the UK define vitamin D deficiency as <25nmol.L-1

Although, these definitions have been subject to recent critique, the unanimous question
which arises amid this jumble is regarding what should be considered the ”optimal level” of Vitamin D. It also raises the question of why there is still no such universal guideline which has been defined until now.

As per de facto, we still lack proper knowledge about the correct supplementation dose. There is now a overwhelming and compelling scientific and epidemiological data suggesting that the human body requires a blood level of Vitamin D ”above” 30 ng/mL for maximum health. To increase the blood level to the minimum 30 ng/mL, it requires the ingestion of at least 1000 IU of vitamin D per day for adults.

In general, there is no downside to increasing one’s vitamin D intake. If you are afraid you are low on vitamin D, you can have your vitamin D status tested by measuring blood levels of 25-(OH)D/vitamin D through a regular blood test performed by your doctor. He or she should then be able to determine if you are deficient, or at risk of becoming deficient, and recommend the proper supplement or dietary protocol available to the health professionals presently.

Symptoms of deficiency to be considered, including unexplained muscle pain and weakness, over-training injury and frequent illness such as respiratory tract infections.

Vitamin D in athletes

Vitamin D recommendations can also be individualized to each athlete’s blood vitamin D concentration, clinical symptoms, diet and belief system. Athletes with insufficient status require supplementation to keep blood vitamin D concentration in the sufficient range if sensible sun exposure is not possible or desired.

Higher doses may be required in them with excess adipose/body size or darker skin, or who take medications affecting vitamin D metabolism. Athletes with deficient status may benefit from short-term, high-dose “loading” regimens under the supervision of a physician.

This protocol of high-dose loading or supplementing once per week, as opposed to daily may be advantageous to the busy athlete, and reduce the chances of forgetting to take supplements.

Surprisingly, there have been a considerable amount of research/study done by different countries to understand the effects and role of Vitamin D in athletic performance.


It seems that the athletic benefits of UV radiation were widely known by the 1930s, at least in Germany.

”It was a well-known fact that physical performance can be increased through ultra-violet irradiation. In 1927, a heated argument arose after the decision by the German Swimmers Association to use the sunlamp, as an artificial aid, as it may constitute an athletic unfairness, doping, so to speak.”

Also, a study of young Finnish female athletes (gymnasts and runners) found that athletes did not differ from non-athletes in either vitamin D intake or serum 25(OH)D levels, and both were more likely than not to be vitamin D–deficient.

In reality, Sixty-seven per cent of these young women had levels below 15 ng/mL during winter which corresponded to their impaired performances. These studies were carried out by different countries to assess any performance variation in their athletes conforming to their Vitamin D levels.

There was also a report validating seven French cyclists, training 16 hours per week had mean Vitamin D levels of just 32 ng/mL-1, surprisingly low for a sport where sun exposure is common.

Ten elite runners from the Swedish national track and field team, in year-round training, displayed maximal oxygen uptake during the summer months correlating the beneficial effects of vitamin D due to sun exposure.

Others found significant summer/winter differences in heart rate variability in 120 healthy male Israeli athletes. In certain cases, lower heart rate variability, which is associated with cardiac pathology, occurred mostly during the winter.

Ten healthy male Japanese students showed a significant seasonal variation in CO2 sensitivity with unexplained improvements in late summer, a rapid decline beginning in
the following September. These research data speaks volumes related to the beneficial effects of Vitamin D reported across different timelines and different countries using varied methodologies.

However, both the theory and any existence of any ideal Vitamin D levels needed for peak athletic performance and optimal health need confirmations by properly conducted interventional trials and an international awakening towards this medical condition.

Read More on SpoBits: Cavort of Soccer Across Continents – A narrative on how football is followed from miles away


Our opinion at Spobits asserts the available findings of the effective impact of Vitamin D that has been shown so far and we encourage our readers to get their vitamin D status checked and start proper supplementation under medical supervision.

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